The goal of the Program Project is to understand how opiate drugs exacerbate the effects of HIV in the CNS. To achieve this goal, we will address the following hypothesis: Opiate drugs, through selective actions at f-opioid receptors (MOR), exacerbate the pathogenesis of HIV-1 by disrupting glial homeostasis, increasing inflammation, and decreasing the threshold for pro-apoptotic events in neurons. Inflammatory processes and viral products released by human immunodeficiency virus type one (HIV-1) infected cells cause widespread metabolic derangement, immune dysregulation, disruption of neuron-glial relationships, and neuronal dysfunction, which contribute to HIV encephalitis and perhaps dementia. Opiate drugs, such as heroin and oxycodone, intrinsically disrupt CNS function, by interfering with endogenous opioid and neuroimmune function. CNS disruption and neurotoxicity are exacerbated when opiates are combined with HIV. Project 1 will examine neurodegenerative mechanisms in opioid and HIV protein-exposed cell cultures and mice. Neuron death and non-lethal effects (e.g., neuritic pruning will be examined in + MOR-expressing populations of striatal neurons in vitro. Signaling between premitochondrial pathways involving PTEN and Akt will be examined for both caspase-3 dependent and independent cell death using pharmacological, transfection (silencing/overexpression vectors) and genetic strategies (MOR-knockout and PTEN-deficient mice). Project 2 will explore opioid and HIV disruption of astroglial function (e.g. Ca2+, oxyradical production, and EAAT1/2 glutamate transporters) and the release of inflammatory cytokines (e.g. TNFa, IL-6) in vitro and in vivo, and will identify aspects of astroglial destabilization that contribute to pathological changes in neurons. Project 3 will examine opioid-HIV-induced changes in free radical production, redox-sensitive intracellular signaling pathways (e.g., proteasome activity/immunoproteasome subunit expression, NFkappaB, MAP kinase) and inflammatory signaling in microglia. Last, studies using conditional transgenic mice expressing Tat or gp120 and severe combined immunodeficient (SCID) mice injected with HIV-infected human monocytes will assess opioid-HIV effects in neurons, astroglia, and microglia in vivo. The Projects are supported by an administrative core (Core A), and a transgenic/SCID mouse core (Core B) and recombinant viral protein core (Core B), and common findings, e.g., on neuronal dysfunction/death will be integrated in Project 1.